A magnetic disk drive includes a rotating magnetic disk and a thin film magnetic head supported by a suspension and positioned in a radial direction of the magnetic disk. The magnetic head reads and writes magnetic data from and to the magnetic disk while relatively traveling over the magnetic disk. The slider of the magnetic head is designed to fly through the assistance of an air lubrication bearing, that is, an air wedge film effect, so that the slider does not come into direct contact with the magnetic disk. In order to realize higher recording density of a magnetic disk drive, and thereby increased capacity and reduced size thereof, it is effective to increase line recording density by reducing a distance between the slider and the magnetic disk, namely, the flying height of the slider.
The conventional design of flying height of a slide has allowed for a decrease in flying height resulting from machining variations, a temperature difference of usage environment, a difference in flying height between read and write and the like and has been provided with a flying height margin in order to prevent contact between the slider and the disk even under the worst conditions. If a slider is used having a capability of adjusting a flying height according to the use conditions for each thin magnetic head, it is possible to eliminate the margin mentioned above and thereby significantly reduce a flying height of a read/write element while preventing the contact between the slider and the disk. Japanese Laid-Open Patent No. 2004-342151 (“Patent Document 1”) proposes a slider structure in which a heater made of a thin film resistive element is provided in the vicinity of a write element and a read element, heats part of the slider as necessary to thermally expand for protrusion, thus adjusting a distance between the write element and the read element, and a magnetic recording medium.
However, if the heater is provided to adjust flying height, then the number of lines in the read and write elements and the number of terminals disposed on the rear end face of the head will be increased. Also the number of lines on the suspension connected to the terminals is increased, thus narrowing each spacing between the lines. This poses a problem of crosstalk from the write element lines to the read element lines during writing. In order to solve the problem of crosstalk, Japanese Laid-Open Patent No. 2004-192742 (“Patent Document 2”) discloses structures in which read element lines are disposed to be put between heater lines on a suspension and in which heater lines are disposed between write element lines and read element lines on the suspension.
A thin film magnetic head is provided on its rear end face with six terminals: two write element terminals, two read element terminals, a heater terminal and a ground terminal. The ground terminal is connected to a ground wire (or ground line) from a slider, ground lines of two electrodes of a read element, ground lines of upper and lower magnetic shields, ground lines of upper and lower magnetic pole pieces of a write element and a ground line of a heater. In this way, since the lines near the ground wire are crowded, if exogenous noise is applied to the ground wire of the slider, then crosstalk noise may occur in the lead wires of the read element, the ground lines of the electrodes, the ground lines of the upper and lower magnetic shields and the ground lines of the upper and lower magnetic pole pieces of the write element. The exogenous noise contains noise caused by a spindle motor for a magnetic disk and the like. Since the crosstalk noise has an adverse affect on the read element and the write element, it is necessary to reduce the crosstalk noise as much as possible.